Good news, platelets are at 48,000, up from 8,000 last Friday! This is the highest level we've seen since this whole thing began 6 weeks ago (on the first day my platelets were 31,000 - normal level is between 150,000 and 350,000). They're also higher than I thought they would be - I expected a boost of 22,000. So it's possible the extra 18,000 are from my own marrow as a result of the chemo, which would be great. We'll know on Wednesday when I do another blood test since platelet lifetime is 3-5 days, so the platelets from this transfusion should be dead by then (weird and kind of grim, huh).
The worry about transfusions is that your immune system might not enjoy another person's platelets running around your body, and could eat them all up. Luckily my immune system seems to have given a collective "ho hum" about the new platelets and let them merrily go along their way.